LANDOVER, Md. – The offensive inconsistencies that have plagued the 49ers for most of the season did not totally disappear against Washington’s 28th-ranked defense.

The offense had its moments. But it also had its typical bouts of malaise, too.

The 49ers’ offense fed off the defense and the passing game had enough moments to help pull away for a 27-6 rout over hapless Washington on Monday night at FedEx Field.

The 49ers (7-4) remain in a battle with the Arizona Cardinals (7-4) for second place in the NFC West as well as the sixth spot in the NFC playoffs. The 49ers defeated the Cardinals earlier this season, and the clubs conclude the regular season against each other on Dec. 29 in Arizona.

Quarterback Colin Kaepernick and the 49ers’ offense struggled in back-to-back losses against Carolina and New Orleans – with top-five ranked defenses. On Monday, it got a whole lot easier.

Kaepernick completed 15 of 24 passes for 235 yards with three touchdowns and no interceptions. It was just the third time in 11 games that Kaepernick has thrown for more than 200 yards in a game this season.

Your browser does not support iframes.

It’s no big surprise Kaepernick relied heavily on wide receiver Anquan Boldin and tight end Vernon Davis to breathe some life into the 49ers’ offense while Frank Gore struggled to find any room against a Washington defense that loaded up to stop the run. Gore finished with just 31 yards on 13 rushing attempts.

Boldin caught a 24-yard pass against the coverage from Washington cornerback Josh Wilson. On the next play, the Kaepernick-Boldin combination again exploited Wilson for a 19-yard touchdown pass to give the 49ers a 7-0 lead.

But the 49ers’ offense floundered for most of first half, carrying a slim 10-6 lead into the locker room at halftime.

Leading 10-6 early in the third quarter, 49ers linebacker Patrick Willis stopped running back Roy Helu for a 1-yard gain on a fourth-and-2 play.

The 49ers’ offense took advantage with Kaepernick again hooking up twice with Boldin. The pair combined on a 32-yard pass. After tight end Vernon Davis’ 20-yard reception, Kaepernick hit Boldin on a 6-yard scoring pass. Kaepernick bought time with his feet and found Boldin running the back line of the end zone.

Boldin’s two receiving touchdowns gives him eight career on Monday Night Football, the most receiving scores for any current player. Boldin finished with 5 catches for 94 yards and two touchdowns. It was Boldin’s best game since his 208-yard performance in Week 1 against the Green Bay Packers.

Your browser does not support iframes.

Kaepernick also added a touchdown pass to Davis late in the third quarter. Kaepernick has 14 scoring passes on the season. Nine have gone to Davis, and the other five have ended in Boldin’s hands.

Cashing in: Safety Donte Whitner intercepted a Robert Griffin pass in the first quarter and returned it 7 yards to the San Francisco 42. Kaepernick hit tight end Vernon Davis for a 40-yard pass to set up Phil Dawson’s 29-yard field goal.

It was the 19th consecutive time the 49ers scored points off a turnover – 11 touchdowns and eight field goals.

It was another rough day for Griffin, a second-year player who led Washington the playoffs as a rookie. Griffin completed just 17 of 27 passes for 127 yards.

Injury concerns: The 49ers played without three starters. Left defenslve tackle Ray McDonald missed his second game with a high-ankle sprain. He has a chance to return to action Sunday against the St. Louis Rams. Tony Jerod-Eddie made his second start in place of McDonald. Left guard Mike Iupati, out for a couple of weeks with a knee sprain, was replaced by Adam Snyder. And cornerback Tarell Brown, who is expected to miss a couple of games with a ribs injury, was replaced by Tramaine Brock.

Crabtree to return: Wide receiver Michael Crabtree will be activated from the reserve/physically-unable-to-perform list on Tuesday, the final day the 49ers have to make such a roster move. The 49ers did not make a roster move with Crabtree prior to Monday’s game. Depending on his week of practice, Crabtree could make his season debut on Sunday against the Rams at Candlestick Park. Crabtree continues to rehab his surgically repaired right Achilles tendon.

Your browser does not support iframes.

This ‘n’ that: Running back Kendall Hunter was on the 49ers’ kickoff coverage unit and he was credited with a tackle on the opening play of the game when return man Niles Paul slipped at the end of a 12-yard return. . .

Mario Manningham had four receptions for 38 yards in his first two games after being activated from a knee injury that ended his season a year ago. In the 49ers’ first three series, Manningham caught three passes for 35 yards. He finished with four receptions for 45 yards.

Outside linebacker Aldon Smith recorded 2 sacks – his first since Week 3 against the Indianapolis Colts. Smith took a voluntary leave of absence following that game to enter into treatment for substance abuse. . .

Your browser does not support iframes.

Ahmad Brooks recorded two sacks to give him a career-high 8.5 on the season. . .

Vernon Davis lost his first fumble since 2011 to end the 49ers’ first series of the second half. Washington cornerback DeAngelo Hall got away with a facemask penalty that would’ve negated the turnover and given the 49ers a first down in Washington territory. . .

LaMichael James had a 40-yard punt return in the third quarter that set up the 49ers touchdown that gave the 49ers a 24-6 lead. Kyle Williams’ longest punt return was 22 yards before he was released two weeks ago. . .

Dawson also made a 49-yard field goal attempt. He has made 13 consecutive attempts. His last miss came in Week 4 and can be excused. It was a 71-yard fair-catch kick attempt.